Electric arc furnaces are characterized by a plurality of electrodes immersed in the molten metal. Each electrode has a holder which often is in the form of a cooper casting with cooling coils of a metal such as Monel or steel embedded in the casting. Copper is employed because of its low electrical resistivity and high heat conductivity.
The holders are characterized broadly by a base by which the holder and electrode are supported, and a bowl which is of general U-shape and surrounds and contacts the electrode. The base has a clamping portion which confronts the electrode and the bowl has a contact surface which confronts and contacts the electrode diametrically opposite the clamping portion of the base.
The contact surface of the bowl is subject to deterioration under the severe conditions of use and must be repaired from time to time. Various ways are known to repair this surface. Among these is the proposal of U.S. Pat. No. 3,151,202, that the deteriorated portion of the bowl be cut off on a diametral plane and scrapped and replaced by a new casting. In that earlier patent, the new casting is a semi-cylindrical casting of copper having a vertically elongated slot cast therein that extends about the full semi-cylindrical extent of the new portion. However, the resulting casting is only a shell and has no sufficient mass and is neither mechanically nor electrically sound. Moreover, the cast copper of such a repair piece is not dense enough to hold water at an elevated pressure and so the repair piece tends to leak. Finally, the cast slot which provides a water chamber is a large void without a flow pattern. Sediment accumulates at the bottom of the void, which keeps the water from contacting and cooling this area. In fact, however, this area is the most critical to the transfer of current to the electrode; and so the area that needs the most cooling receives the least.
It is accordingly an object of the present invention to provide a method of repairing an electrode holder of the type described, in which the heat exchange characteristics of the original holder will be substantially improved or will at least be unimpaired.
Another object of the present invention is the provision of such a method, in which the repair can be effected without performing a casting operation.
Still another object of the present invention is the provision of such a method, in which the repair can be effected using only commercially available materials.
It is also an object of the present invention to provide such a method of repair, which will be rapid and economical to perform, and whose repaired product will be rugged and durable in use.